1. Field of the Invention
The present invention relates to a control device for a type of receptacle, and particularly to a control apparatus for master/slave outlets, with which a most simplified circuit can perform a function that the slave outlet only supplies the power at the time of the master outlet having supplied the power thereof under a condition of fulfilling safety codes regulated by all countries in the world.
2. Description of Related Art
A common power strip usually applies a switch to control if each of the outlets offers the power. However, due to the computer getting popular with versatile developments, a new style of the power strip in the market has been designed in this way that one of the outlets thereof is designated as a master outlet and the rest are designated as slave outlets. Wherein, the master outlet is powered on for supplying the current to the computer first and slave outlets (usually are connected to the periphery) then can be powered on afterward so that the periphery connected to the slave outlets can be powered off as soon as the computer is turned off or in a state of sleep mode.
Referring to FIG. 1, a block diagram of a conventional control apparatus for a power strip is illustrated. It can be seen in FIG. 1 that the control apparatus comprises an outlet control device 1, a plug 2, a master outlet 3 and at least a slave outlet 4. The outlet control device 1 further comprises an isolated current sensor 11, an amplifying and comparing circuit 12, a driver 13, a relay 14 and an isolated power supply 15.
Wherein, the isolated current sensor 11 is isolated from the alternate current of the master outlet and can be induced with a current signal. The amplifying and comparing circuit 12 is used for amplifying the induced current generated by the insulated current sensor 111 and sending the amplified induced current to a comparator 121 for comparing with a required reference voltage. If the voltage of the amplified current is greater than the reference voltage, a start signal is sent to the driver 13 to actuate the relay 14. The isolated power supply 15 is used for supplying the direct power source needed by the amplifying and comparing circuit 12, and by relay 14.
However, it is required for the conventional power strip during being designed to meet the safety regulations of all countries so that required safety spaces of the master outlet 3 and the slave outlet 4 have to be considered in the electronic circuit. Hence, the insulation parts, such as the isolated current sensor 11 and the isolated power supply 15, have to be installed and in this way, it results in an increased cost of the circuits.